With a lot of "cutting corners" and ignoring details, I think I can barely pull it off. It's going to be rough though.
I have the chest+abdomen shaped but not assembled, and I have the vambraces and rerebraces shaped as well, and am working on the pauldrons. Haven't started on the back, neck, or legs yet. Or much of the painting (which thankfully will be pretty light, mostly just the red/white stripe on the right side, and edging and the like).
Oh yes, Ironman is totally doable. People make those out of the same foam I'm using.